1. Field of the Invention
The present invention relates to elevator safety devices. More particularly, the invention relates to a mechanical elevator hoistway door closer for increasing the closing force on the elevator hoistway door as the door approaches the door closed position to overcome wind velocities and air pressurizations in elevator hoistways.
2. Description of the Prior Art
Modern elevator installations typically comprise a hoistway door assembly 10 with one or more hoistway door panels 41 on each landing to block access to the hoistway when the elevator cab is not present. As shown in FIG. 1, hoistway door panels 41 are typically suspended from the hoistway header 16 by a plurality of hangers 11. The panels 41 are usually affixed to the hangers 11 with conventional mounting bolts 14. The hangers 11, which usually comprise one or more pulleys 12, allow lateral translation of the door panels 41 along a track 15 affixed to the hoistway header 16. A relating cable 17 is generally provided in multiple panel installations in order to coordinate the opening and closing of the panels 41. As is generally known to those of ordinary skill in the art, a relating cable door clamp 18 affixed to one hoistway door panel 41, and a relating cable dead end clamp 19 affixed to the other hoistway door panel 41 establishes the desired operating relationship between the panels 41.
As is also known to those of ordinary skill in the art, the hoistway panels 41 of a hoistway door assembly 10 are opened and closed in normal operation through interaction with the cab door (not shown) as the cab comes to rest at a particular landing. In particular, a power door-operator, which is normally located atop the cab, opens or closes the cab door through a drive arm, cable, belt, screw drive, or the like. A clutch mechanism engages a roller assembly 20 to couple the cab door to the hoistway door assembly 10 for opening and closing. A vertically disposed clutch on the cab door then engages an upper clutch roller 22 and lower clutch roller 23 as the cab settles upon a landing. Because the lower clutch roller 23 is generally offset from the upper clutch roller 22, engagement of the clutch with the rollers 22, 23 serves to release a mechanical latching device 25 through an interposed clutch linkage 24. Release of the mechanical latching device 25 allows the hoistway door panels 41 to be opened as a lateral force is applied from the cab door to the rollers 22, 23 through the clutch.
As the cab prepares to leave a particular landing, the power door operator reverses the position of the drive arm (or other device) to force the cab doors closed. The clutch engages the rollers 22, 23 from their side opposite that engaged during the opening operation, thereby forcing the hoistway door 41 closed and re-engaging the mechanical latching device 25. Additionally, electrical contacts 26, typically collocated with the mechanical latching device 25 in an interlock assembly, will then signal the elevator controller to confirm that the hoistway door 41 has in fact been closed, enabling the elevator cab to depart the landing.
Because the device 25 may fail, however, additional safety devices are generally required in order to ensure that the hoistway door panels 41 close and remain closed if, for any reason, the elevator cab leaves the landing prior to door closing. Typically, a door closer device 27 is provided to facilitate and ensure closing of the hoistway door panels 41. In the past, the door closer device 27 has generally comprised a closer reel attached to one of the hoistway door assembly 10 by a bearing or bushing assembly 30 located in a passage 42 around the central axis 31 of the door closer device 27. A spring 32 within a spring cavity 28 engages a ratchet 29 within the door closer device 27 to produce tension on a closer reel cable 33, which may be extended from the door closer device 27. A distal end of the closer reel cable 33, generally terminated with a cable eyelet 34, is fixedly secured to the hoistway header 16 through a cap screw 35. As is known to those of ordinary skill in the art, however, the cable eyelet 34 may, in multiple door installations, be affixed to a second hoistway door panel 41. Likewise, as is known to those of ordinary skill in the art, the door closer device 27 could be affixed off of the hoistway door assembly 10—for example, on the hoist-way header 16, while the cable 33 is affixed to one of the door panels 41.
In operation, as the hoistway door panels 10 open, the closer reel cable 33 is extended from the door closer device 27. As the closer reel cable 33 is pulled from the doors closer device 27, increasing opposing force is applied on the reel cable 33 from the spring 32. In the event of an electrical or mechanical failure preventing the otherwise normal closing of the hoistway door 10, tension on the closer reel cable 33 serves to ensure 15 that the hoistway door 10 closes and remains closed. Unfortunately, elevator hoistway door closers as presently known the art are often ineffective in extreme conditions.
In windy areas, such as coastal or lakeshore regions, or in air conditioned buildings with windows that may be opened, an inrush of air is often created during heavy traffic hours as a result of the negative pressure in the building. This inrush of air causes an air current in the hoistway, which acts as an air duct. As the elevator cab reaches a landing, air pressure within the hoistway escapes rapidly through the hoistway door assembly 10. As the door panels 41 attempt to close, a jet nozzle effect is created whereby the resultant high wind velocity puts such a stress on the hoistway door assembly 10 that the door panels 41 often fail to close, causing the elevator to initiate a recycle mode. In this condition, the known door closer devices 27 are generally unable to force the hoistway door panels 41 to close. To date, the solution to this problem has resided in a call-back for maintenance for the elevator. In response to the call-back, the service technician generally adds a loop of the closer reel cable 23 about the closer reel, thereby increasing tension on the spring 32. Unfortunately, as wind conditions change, or traffic flows through the building lessen, the excess tension on the closer reel cable 33 can cause the hoistway door panels 41 to close too rapidly in the absence of the jet nozzle effect. The door panels 41 come together with excess force, and the result is again that the elevator enters a recycle mode and fails to operate. To date, as before, the typical response has been yet another maintenance call-back where the service technician will remove the previously added cable loop from about the closer reel. Door closure problems are presently the leading cause of elevator service calls.
Therefore, a need exists for a new and improved closer device that can be used for elevator hoistway doors. In this regard, the present invention substantially fulfills this need. In this respect, the closer device according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of overcoming wind velocities and air pressurizations in elevator hoistways.